<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #d1{
            width: 100px;
            height: 100px;
            border: 10px solid red;
            /*圆角:值越大越圆,超过宽高一半时为正圆*/
            border-radius: 60px;
        }
        #d2{
            width: 50px;
            height: 100px;
            border: 1px solid red;
            /*内边距会影响元素的宽高*/
            padding-left: 50px;
        }
    </style>
</head>
<body>
<div id="d2">内边距</div>
<div id="d1"></div>
</body>
</html>